638238813 has 8 divisors (see below), whose sum is σ = 865408800. Its totient is φ = 418280688.

The previous prime is 638238787. The next prime is 638238857. The reversal of 638238813 is 318832836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 638238813 - 2⁹ = 638238301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638238883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1802758 + ... + 1803111.

It is an arithmetic number, because the mean of its divisors is an integer number (108176100).

Almost surely, 2^638238813 is an apocalyptic number.

It is an amenable number.

638238813 is a deficient number, since it is larger than the sum of its proper divisors (227169987).

638238813 is a wasteful number, since it uses less digits than its factorization.

638238813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3605931.

The product of its digits is 165888, while the sum is 42.

The square root of 638238813 is about 25263.3887869383. The cubic root of 638238813 is about 860.9826576356.

The spelling of 638238813 in words is "six hundred thirty-eight million, two hundred thirty-eight thousand, eight hundred thirteen".